Six-axis force sensor for robots

Abstract

The application discloses a six-dimensional force sensor suitable for a robot in the technical field of force sensors, which comprises a cover, a shell, an elastic main body, an upper platform of the elastic main body, a lower platform of the elastic main body and strain gauges; the inner wall of the shell is provided with a shell baffle which is in a circular ring structure and divides the internal cavity of the shell into an upper cavity of the shell and a lower cavity of the shell; the elastic main body is connected by hinges and connecting beams and has an overall structure in an S shape; one side of each hinge is a plane and the other side is a circular arc surface; the connecting beams are in a cuboid structure and each are provided with a strain gauge on the circular arc surface of each hinge; the upper end of the elastic main body is fixed together with the upper platform of the elastic main body, and the lower end of the elastic main body is fixed together with the lower platform of the elastic main body. The six-dimensional force sensor has small decoupling errors of forces / torques in all directions, good isotropy, relatively close sensitivities, large sensitivity, large deformation of each hinge, large voltage output and strong anti-interference capability.

Description

Technical Field

[0001] This invention relates to a six-dimensional force sensor in the field of force sensor technology, and in particular to a six-dimensional force sensor suitable for robots that can effectively solve the problem of easy breakage of elastic columns during grinding. It has a large range of lateral force and lateral torque. Background Technology

[0002] Six-dimensional force sensors can simultaneously measure three orthogonal forces and three orthogonal moments, and are widely used in industry and research. The trend towards industrial automation has led to an increasing reliance on robots in various jobs and applications, such as assembly, welding, grinding, and deburring. To effectively control robots and ensure their flexible operation, it is necessary to accurately detect the interaction forces between the robot and its environment and to optimize performance through braking mechanisms.

[0003] However, the range of traditional six-dimensional force sensors in the Z direction is much larger than that in the X / Y directions, and there is also a significant difference in sensitivity, with poor isotropy in the three dimensions. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a six-dimensional force sensor suitable for robots. It features small decoupling errors in force / torque across all directions, good isotropy (i.e., similar ranges and sensitivities in the XYZ directions), high sensitivity, large deformation of each hinge, high voltage output, and strong anti-interference capability.

[0005] This invention is achieved through the following technical solution: The invention includes a cover and a shell, characterized by further including an elastic body, an upper platform of the elastic body, a lower platform of the elastic body, and strain gauges; a shell baffle is arranged on the inner wall of the shell, the shell baffle having a circular ring structure, dividing the internal cavity of the shell into an upper shell cavity and a lower shell cavity; the elastic body is connected by a hinge and a connecting beam, and the overall structure is "S"-shaped; one side of the hinge is a plane, and the other side is an arc surface; the connecting beam has a cuboid structure, and a strain gauge is arranged on each of the arc surfaces on both sides of the hinge; the upper end of the elastic body is fixedly connected to the upper platform of the elastic body. The lower end of the elastic body is fixed to the lower platform of the elastic body; the overall structure consisting of the upper platform of the elastic body, the elastic body, and the lower platform of the elastic body is arranged inside the cavity of the shell, with the upper platform of the elastic body arranged in the upper cavity of the shell and the lower platform of the elastic body arranged in the lower cavity of the shell; the cover is arranged on the top of the shell, with a cover through hole arranged on the cover, and an upper platform threaded hole arranged on the upper platform of the elastic body, the cover through hole and the upper platform threaded hole being connected by bolts; the shell baffle is arranged with a shell threaded hole, and the lower platform through hole is arranged on the lower platform of the elastic body, the lower platform through hole and the shell threaded hole being connected by bolts.

[0006] Furthermore, the present invention also includes a cover threaded hole and a lower platform threaded hole; the cover threaded hole is arranged on the upper surface of the cover for connection with the force-applying component; the lower platform threaded hole is arranged on the lower surface of the lower platform of the elastic body for fixing the sensor.

[0007] Furthermore, in this invention, there are six through holes in the cover, six threaded holes in the upper platform, six threaded holes in the housing, six through holes in the lower platform, six threaded holes in the cover, and six threaded holes in the lower platform, which are evenly distributed along the circumference.

[0008] Furthermore, in this invention, the elastic body includes six hinges and seven connecting beams. The upper end of the elastic body is fixed to the upper platform of the elastic body via hinges, and the lower end of the elastic body is fixed to the lower platform of the elastic body via hinges. Except for the two hinges connected to the upper platform and the lower platform of the elastic body, the two ends of the other four hinges are connected to the connecting beams.

[0009] Furthermore, in this invention, the six hinges and seven connecting beams are integrally formed.

[0010] Compared with the prior art, the present invention has the following beneficial effects: the present invention is reasonably designed, has a simple structure, small decoupling error of force / torque in each direction, good isotropy, that is, the ranges of XYZ are relatively close, and the sensitivity is relatively close; and the sensitivity is large, the deformation of each hinge is large, the voltage output is large, and the anti-interference ability is strong. Attached Figure Description

[0011] Figure 1 This is an overall structural diagram of the sensor device in Embodiment 1 of the present invention;

[0012] Figure 2 This is a top view of Embodiment 1 of the present invention;

[0013] Figure 3 yes Figure 2 Schematic diagram of the structure of section AA in the middle;

[0014] Figure 4 This is a bottom view of Embodiment 1 of the present invention;

[0015] Figure 5 This is a top view of the lid in Embodiment 1 of the present invention;

[0016] Figure 6 yes Figure 5 Schematic diagram of the structure of the middle BB section;

[0017] Figure 7 This is a top view of the shell in Embodiment 1 of the present invention;

[0018] Figure 8 yes Figure 7 Schematic diagram of the CC section;

[0019] Figure 9 This is a schematic diagram of the structure of the elastic body in Embodiment 1 of the present invention;

[0020] Figure 10 This is a front view of the elastic body in Embodiment 1 of the present invention;

[0021] Figure 11 This is a left view of the elastic body in Embodiment 1 of the present invention;

[0022] Figure 12 These are the hinge structure diagram and strain gauge diagram of Embodiment 1 of the present invention;

[0023] Figure 13 This is a cross-sectional view of the overall structure of the sensor device in Embodiment 2 of the present invention;

[0024] Figure 14 This is a schematic diagram of the structure of the elastic body in Embodiment 2 of the present invention;

[0025] Among them, 1. Cover, 2. Elastic body, 3. Shell, 101. Threaded hole of cover, 102. Through hole of cover, 201. Upper platform of elastic body, 202. Threaded hole of upper platform, 203. Hinge, 204. Connecting beam, 205. Strain gauge, 206. Lower platform of elastic body, 207. Through hole of lower platform, 208. Threaded hole of lower platform, 301. Threaded hole of shell, 302. Shell baffle, 303. Upper cavity of shell, 304. Lower cavity of shell. Detailed Implementation

[0026] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These embodiments are based on the technical solutions of the present invention and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0027] Example 1

[0028] like Figures 1 to 12As shown, the present invention includes a cover 1, an elastic body 2, a shell 3, a cover threaded hole 101, a cover through hole 102, an upper platform 201 of the elastic body, an upper platform threaded hole 202, a hinge 203, a connecting beam 204, a strain gauge 205, an elastic body lower platform 206, a lower platform through hole 207, a lower platform threaded hole 208, a shell threaded hole 301, and a shell baffle 302; a shell baffle 302 is arranged on the inner wall of the shell 3. The shell baffle 302 has a circular structure and divides the internal cavity of the shell into two parts: an upper shell cavity 303 and a lower shell cavity 304. The elastic body 2 is formed by hinges 203 and connecting beams 204, and the overall structure is "S" shaped. The elastic body 2 includes six hinges 203 and seven connecting beams 204. The upper end of the elastic body 2 is fixed to the upper platform 201 of the elastic body through hinges 203, and the lower end of the elastic body 2 is fixed to the lower platform 206 of the elastic body through hinges 203. Except for the two hinges 203 connected to the upper platform 201 and the lower platform 206 of the elastic body, the two ends of the other four hinges 203 are connected to the connecting beams 204. The uppermost horizontal section of the elastic body 2 consists of two connecting beams 204 and one hinge 203, the middle horizontal section consists of three connecting beams 204 and two hinges 203, and the lowermost horizontal section consists of two connecting beams 204 and one hinge 203. One side of hinge 203 is flat, and the other side is curved. Connecting beam 204 has a cuboid structure, with a strain gauge arranged on each of the curved surfaces on both sides of hinge 203. The integral structure consisting of upper platform 201, elastic body 2, and lower platform 206 of elastic body is arranged inside the cavity of shell 3. Upper platform 201 of elastic body is arranged in the upper cavity 303 of shell, and lower platform 206 of elastic body is arranged in the lower cavity 304 of shell. Cover 1 is arranged on the top of shell 3. Cover 1 has a cover through hole 102. Upper platform threaded hole 202 is arranged on upper platform 201 of elastic body. Cover through hole 102 and upper platform threaded hole 202 are connected by bolts. Shell baffle 302 has shell threaded hole 301. Lower platform through hole 207 is arranged on lower platform 206 of elastic body. Lower platform through hole 207 and shell threaded hole 301 are connected by bolts. The cover threaded hole 101 is arranged on the upper surface of the cover 1 for connection with the force-applying component; the lower platform threaded hole 208 is arranged on the lower surface of the lower platform 206 of the elastic body for fixing the sensor. There are six cover threaded holes 101, cover through holes 102, upper platform threaded holes 202, lower platform through holes 207, lower platform threaded holes 208, and housing threaded holes 301, which are evenly distributed along the circumference.

[0029] In the implementation of this invention, when an external force / torque is applied to the elastic body, the strain gauge 205 on the hinge 203 deforms, and the force / torque on each joint is obtained by outputting an electrical signal. Using a transposed Jacobian matrix, the force / torque in the operating space can be mapped to the force / torque output in the joint space, thus allowing the force / torque on the sensor to be calculated from the electrical signal output by the joint. The specific measurement principle is as follows:

[0030] The force / torque output by the joint is: τ=[τ1 τ2 … τ n ] T

[0031] The joint movement speed is:

[0032] In the formula, n represents the degrees of freedom (number of joints) in the joint space.

[0033] The total power output of the system (equal to force multiplied by velocity) in joint space is expressed as:

[0034] From the perspective of operational space, let the force / torque that the terminal can output to the outside world at this time (or the force / torque exerted by the outside world on the terminal to maintain the static equilibrium of the entire system) be:

[0035] F = [f1 f2 f3 n1 n2 n3] T

[0036] Where f represents force and n represents torque.

[0037] The terminal speed is:

[0038] The power of the work done by the external force applied to the terminal on the entire system is:

[0039] According to the law of conservation of energy,

[0040] Substituting the instantaneous kinematics formula into the equation:

[0041]

[0042] τ T =F T J = (J T F) T

[0043] τ=J T F

[0044] F = [J] T ] -1 τ

[0045]

[0046] In the formula, J is the Jacobian matrix. The Jacobian matrix has m rows and n columns: m is the degree of freedom in the operating space, n is the degree of freedom in the joint space (number of joints), x is the velocity of the end effector, and q is the joint motion velocity. The transpose of J multiplied by the force / torque in the operating space yields the force / torque output in the joint space. F is the force / torque experienced by the sensor, and τ is the force / torque experienced by the joint, obtained from the output signal of the strain gauge.

[0047] Example 2

[0048] In Embodiment 1, the six hinges 203 and seven connecting beams 204 included in the elastic body 2 are separate structures; in this embodiment, the six hinges 203 and seven connecting beams 204 are an integrally formed structure, such as... Figure 13 and Figure 14 As shown.

[0049] The above embodiments are merely illustrative of the design principles and uses of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A six-dimensional force sensor suitable for robots, comprising a cover and a housing, characterized in that... It also includes an elastic body, an upper platform of the elastic body, a lower platform of the elastic body, and strain gauges; A shell baffle is arranged on the inner wall of the shell. The shell baffle has a circular structure and divides the internal cavity of the shell into two parts: the upper cavity and the lower cavity. The elastic body is connected by hinges and connecting beams, and the overall structure is "S" shaped; one side of the hinge is a plane and the other side is an arc surface; the connecting beam is a cuboid structure, with a strain gauge arranged on each of the arc surfaces on both sides of the hinge. The upper end of the elastic body is fixed to the upper platform of the elastic body, and the lower end of the elastic body is fixed to the lower platform of the elastic body; the overall structure consisting of the upper platform of the elastic body, the elastic body, and the lower platform of the elastic body is arranged in the internal cavity of the shell, with the upper platform of the elastic body arranged in the upper cavity of the shell and the lower platform of the elastic body arranged in the lower cavity of the shell. The cover is located on the top of the shell, and a cover through hole is provided on the cover. An upper platform threaded hole is provided on the upper platform of the elastic body. The cover through hole and the upper platform threaded hole are connected by bolts. A shell threaded hole is provided on the shell baffle, and a lower platform through hole is provided on the lower platform of the elastic body. The lower platform through hole and the shell threaded hole are connected by bolts. It also includes a cover threaded hole and a lower platform threaded hole; the cover threaded hole is arranged on the upper surface of the cover for connection with the force-applying component; the lower platform threaded hole is arranged on the lower surface of the lower platform of the elastic body for fixing the sensor; The cover through hole, the upper platform threaded hole, the shell threaded hole, the lower platform through hole, the cover threaded hole, and the lower platform threaded hole are all six in number and are evenly distributed along the circumference. The elastic body includes six hinges and seven connecting beams. The upper end of the elastic body is fixed to the upper platform of the elastic body through hinges, and the lower end of the elastic body is fixed to the lower platform of the elastic body through hinges. Except for the two hinges that are connected to the upper platform and the lower platform of the elastic body, the two ends of the other four hinges are connected to the connecting beams. The six hinges and seven connecting beams are integrally formed structures.

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